Below is how I treat my sore foot after a long run.
[updated entry] Long runs for me are 10Ks or longer, but I start feeling sore once I do 10 miles or more. To treat my sore foot, I use ice in a water bottle which I’ve kept frozen in my fridge. To use it, I simply put the bottle on the floor and roll my sore foot on it for 15 minutes. It works very well.